We bought a Dell/EMC Unity 350F SAN at work. It’s fast. It does what it says on the tin but we got very close to filling it up and this caused problems for VMware.

When we hit 90% full on the SAN, VMware refused to allow storage vmotion migrations and creation of new VMs. Even when we cleared some space, it still refused to allow us to migrate virtual servers.

Here is what I did to get us out of this hole. Login to the terminal of your VCSA 6.7 appliance

Stop the vcenter service using:

# service-control --stop vmware-vpxd

Connect to the vCenter database using:

/opt/vmware/vpostgres/current/bin/psql -d VCDB -U vc

The password for the vCenter DB can be found in the below file:

/etc/vmware-vpx/vcdb.properties file

Run this query to list the datastores in your vcenter:

select id,thin_prov_space_flag from vpx_datastore;

This will give you a list of datastores as VCDB id numbers with the thin_prov_space_flag displayed as 1 or 0. The datastores with the flag set to 1 will not allow migrates and VM creation on them. This next sql query will set the flag to 0

update vpx_datastore set thin_prov_space_flag=0 where id=<enter-your-id>;

Once you have set the datastore flags to ), quit the sql command line with \q. Then start the web client service using:

# service-control --start vmware-vpxd

Now you can login back to vCenter and migrate your VMs. Be careful as the whole reason you ended up in this state was due to a lack of free disk space on the SAN.